Roughly one in 10 Americans says they have an allergy to the most reliable antibiotic in the world — penicillin. But a handful of immunologists around the country, including at Vanderbilt Medical Center, are trying to reverse the common diagnosis.
The latest science shows a true penicillin allergy is serious but rare, even among those who have the label in their medical chart. Most patients who've been told they have the allergy are probably fine, says Elizabeth Phillips, an adverse drug reaction expert at Vanderbilt.
"When I say most, that would be 95 percent or more of patients that are labeled are not truly allergic to penicillin," she says.
In 2016, the Centers for Disease Control released guidance to physicians explainining the new thinking and urging them to probe deeper when a patient discloses a penicillin allergy. In the past, doctors have generally erred on the side of caution and taken their word for it.
The diagnosis usually comes before age 3. Katie Lipscomb, a mother from Franklin, suffered from frequent earaches as a child and regularly took some form of penicillin. She also had occasional reactions.
"I would always just break out in hives around my hands, my elbows, my knees. It was really weird," she says.
So they figured penicillin was the culprit.
But that allergy label still follows her. When she gave birth to her children, she had to wear a red band to warn hospital staff. When she sees a new doctor, she still lists the wonder drug on her medicine allergies.
"I've just always put penicillin, because that's what I was always told," Lipscomb says.
No one ever asked how she knew, even though studies now show kids usually grow out of the allergy.
But the immunologists working on this project at Vanderbilt admit they have misdiagnosed patients themselves.
"Even in my own practice, some of the things I called penicillin allergy, I don't think that they really were," says Cosby Stone. "But I didn't know what else to call them."
They've developed an online questionnaire to determine who really is at high risk of a reaction. Those identified with low risk, like mild, unconfirmed reactions in childhood, may be given the medication just to see what happens. Stone says that will catch roughly 60 percent of patients with a penicillin label. Others will have skin testing done first.
Even though there are alternatives, penicillin is often the cheapest and most effective antibiotic, especially when given to patients before surgery to preempt an infection. And the non-penicillin options are broader spectrum antibiotics, Stone says, which can add to the nation's superbug problem related to overprescribing.
"I think we actually have a great opportunity to change medical practice," Stone says. "We probably have 10 years of re-educating ourselves on penicillin allergy ahead of us."